Stay-bolt tap



Sept. 16 1924.

G. M. BRUBAKEYR, "JR

STAY. BOLT 'MP Filed Jan. 24 1924 TTORNEY Patented Sept. 16, 1924.

UNITED STATES PATENT OFFICE.v

GORDON MARK BRUBAKER. JR., OF MILLERSBURG, PENNSYLVANIA, ASSIGNOR T0 W. L. BRUBAKER & BROS, COMPANY, OF MILLERSBURG, I',"ENN'SYLVANIA4 STAY-BOLT TAP.

Application led January 24, 1924. Serial No. 688,232.

T o all whom t may concern.'

Be it known that I, GORDON MARK BRU- BAKER, Jr., a citizen of the United States, residing at Millersburg, in the county of Dauphin and State of Pennsylvania, have invented new and useful Improvements in Stay-Bolt Taps, of which the following is a specification.

My invention relates to staybolt taps, and particularly to improvements in staybolt taps of the type shown in my prior Patent No. l, 434,870, dated November 7, 1922, such tap having a forward tapered reaming portion and a following tap portion, the latter comprising a forward threading surface continuous with said reaming portion and composed of tapered threads of successively and progressively increasing diameter and a rear threading surface composed of threads of like diameter, the said tapered threads being continuous with the reaming portion and the said threads of-like diameter being continuous with and corresponding in diameter to the final thread of largest diameter of said tapered threads. This patented tap structure is also provided with spiral clearance grooves extending continuously along the reaming and threading portions and producing spiral ribs having shear-cut reaniing edges and on which the threading surfaces are formed, the threads of which surfaces extend across the ribs at an angle to the axis of the tool.

In my aforesaid patented tap, the grooves and ribs of the reaming and threading portions, which are continuous with each other, extend spirally in the same direction. With such a construction, the chips from both the reaming and threading cutters feed in a common direction, i.e., rearwardly, along the utesl This tends to cause clogging of the flutes and difiicult-y in starting the tool, as well as a tendency on the part of the reaming portion to lag during its working action, owing to the resistance set up by the mass of chips, especially in the operation of simultaneously reaming a hole in an inside boiler sheet and tapping a hole in an outside boiler sheet. l

The object of my present invention is to provide a construction in which this objection is overcome, by extending the ribs and flutes of the reaming and threading portions spirally in opposite direc-tions, as 'hereinafter fully described.

ln the accompanying drawing, illustrating the invention,- p

Figure l is a view in side elevation of a staybolt tap embodying my invention.

Figures and 3 are cross-sections taken@ t respectively, on the lines 2N2 and 3*-3 of Figure l.

Referring now more particularly to the drawing, l designates the shank of the tool which comprises the vforward reamer poi-,y

shown, the tap portion 3 has two threaded.

surfaces, to wit, a forward threaded cutting surface extending between the points 6 and 7 and composed of tapered threads-8, anda rear threaded finishing. surface extending between the points 7 and 9 andcoinposcd.

of uniform threads 10, said threading sur-- faces intersecting at the point 7. Also, shown, the reainer portion 2 ext-ends from the extreme forward end of the tool to the point 6, and the shank tapers from the point 7 to such eXtreme forward end of the tool. 'i

The shank is formedl with longitudinal flutes, or grooves 11-11 producing thi` spiral ribs 12-12, on which ribs 12 the threads 8 and 10 are formed. Each groove 11 of the threadingportion iscontinuous with a groove. 11. of the reaming portion, and eachrib 12 ofthe threading portion isalso continuous with arib 12 of the reaming portion. The grooves 11-11 andl ribs 12-12 thus extend the full distance from the forward end of the tool to the point of intersection 9 between the working portion of the shank and the tang 4, the grooves providing clearance channels for the reception and discharge of the chips from both the reaniing and the threading cutters, and the edges 13 of the ribs l2 forming the acting reaming cutters In the use of the tool, constructed as abo-ve described, and as fully set forth in my aforesaid prior patent, the cutting edges of the reainer portion are employed to ream out the hole which is to be threaded, which operation is followed by the coarse cutting of the threads by the tapered threading surface 8 and the finishing of the threads by the uniform threading surface 10.

The essence of the present invention conlso and ribs. vThis arrangement 'of the grooves *and Tihsof the/@threading and roam-ing portions may Abe so lna'd'e in order that the threaded arrangement may correspondwith that-fused in ordinary practicehnt, if desired, then/grooves 11 and ribs 12 may be Il and :ribs T2" leftharrd grooves A:nid ribs, Withotvdfparting dfrom the Aspirit of the in described, tfheoperatiion of sinnrltaneonsly Teaming n'hole in an inside boiler sheet and tipin'g aho'le in an outside boiler sheet is ered much easier :ind more expeditious. ln-fsu'chmperation, it 'will be understood that `tthe 'time the remer is heginning its out 0h 'the second sheet,` the tap portion is heits,` t'ut on the sheet. 'With e Ytoolof'"o'rdi'nFI- v construction, `under such conditions the 4flutesv'voul'd he more or less the .cl'rips `from the. vfirst rezoning on't,"whi"clh s'et up a resistance to 'the starting "ott theftp portion'ald tend to snhseqnentiy "cause fling 'int-he work -ot this porti-'0n of the tool in making its threading cut. By,

"tions," this ohjeeti'i'on is overcome, since the Chips from thereaining lout will `feed in one direction, inthe present instance forwardly, While thel 'chipsxfrom ythe threading cut will y'reed 'in the opposite direction, in the present instance rearwardly, the ,'bove assuming that'the roaming portion lextends on ,n right hund spiral and the trip portion on a left hand spiral. The saine result would also be gained by e. reverse'. arrangement of the spirals, that is, by ext-ending the reamer spiral in n left hond direction and the tap portion spiral in e right hond direction as will be readily understood. As a result, the learner will secure a better cutting hold on the second sheet fand lassist in feeding the tap portion on its Work, While none of the chips formed by the reamer will run back into the flute of the tap portion and canse such tap portion to `Clog or become hot from undue friction fhecanse ot excessive Work. The

Working operation of the tool is, therefore,`

not only rendered easier, but 'cleaner and better Work may be done in 'much less time.

Having thus fully described my inven tion, I claimz* i. A striybol-t tap having a ream'ingfpoi tion and e threading portion and clearance grooves extending continuously` along s'aid portion and forming ribs on which the vcutting edges oi the reemer and threads 4of the threading portion are formed, the grooves fand ribs of the reaming and threading portions extending spirally in reverse directions. l

v2. A steyholt tap having a forward reaming portion and a rear tap portion, grooves extending cr 1iiti1ii.i( i1sly along seid portions and ilorniiijig r'i'los, the ribs `of the renin-ing 'portion 'being provided with cuttingedges and the ribs Iof the threading portion with GORDON MARK BRUBAKER, Jn. 

